Surface sander having automatic leveling properties



April 21, 1 964 N. L. TEMPERO SURFACE SANDER HAVING AUTOMATIC LEVELING PROPERTIES 3 Sheets-Sheet 1 Filed Dec. 26, 1962 INVENTOR. NICHOLAS L. TE MPERO BY 840M gun-4*.

ATTORNEY 'FIG.2

A ril 21, 1964 N. L. TEMPERO 3,129,539

SURFACE SANDER HAVING AUTOMATIC LEVELING PROPERTIES Filed Dec. 26, 1962 3 Sheets-Sheet 2 FIG. 5

INVENTOR. NICHOLAS L. TEMPERO BY 5mm gm A T TORNE Y A ril' 21, 1964 L TEMPER 3,129,539

SURFACE SANDER HAVING AUTOMATIC LEVELING PROPERTIES Filed Dec. 26, 1962 3 Sheets-Sheet 3 INVEN TOR. NICHOLAS L. TEMPERO ATTORNEY United States Patent 3,129,539 SURFACE SANDER HAVING AU'IGMATIC LEVELING PRGFERTIES Nicholas L. Tempero, 1939 N. Howard St, Akron It), Ghio Filed Dec. 26, 1962, Ser. No. 247,4il3

14 Elairns. (Cl. 51-177) This invention relates to the art of surface finishing equipment and particularly has reference to improvements in floor sanders of the type conventionally used to finish wooden or other types of floors.

It has long been known in the prior art that a revolving, or otherwise moving abrasive material, can be placed in contact with a floor surface to thus impart a smooth finish to the same. Machines of this type employing various types and forms of sanding or other abrasive materials have long been known in the prior art.

While such machines have been known as indicated above, the same have, nonetheless, been possessed of certain inherent disadvantages. art relates to the inability of present type machinesto The principal disadvantage now existent in the prior provide a perfectly level floor surface. In this regard, it is the usual instance that the surface being sanded or otherwise finished includes certain surface irregularities such as high or low spots. Accordingly, the housing supporting the moving sanding means will invariably follow the original contour of the floor surface, with the result that unevenness in the unfinished floor surface will be duplicated in the finished floor surface due to the fact that as the housing moves up or down upon the encountering of surface irregularities there will occur an equivalent up or down movement of the sanding means that is associated therewith. Such irregularity in finished surfaces is, of course, objectionable in many instances such as in bowling lanes.

It has been discovered that the above described disadvantage can be obviated by providing adjusting means between the main housing and the relatively movable sanding means that are associated therewith. More specifically, it has been found that if the main housing is equipped with sensing apparatus that will move relatively of the housing in response to the encountering of surface variations, that this sensing device can be used to actuate certain leveling mechanisms that are provided at the points of interconnection between the main housing and the relatively movable sanding or finishing means. In this fashion, when surface irregularities are encountered by the advancing sander, the same will be instantaneously detected by the sensing apparatus which, in basic simplicity, will send a requisite signal to the leveling mechanism to thus initiate operation of the same to make the appropriate adjustment and thus continue maintenance of the sanding mechanism in a constantly uniform plane.

Thus, for example, if a raised protuberance is encountered by the advancing machine, the front portion of the main housing will tilt upwardly to be inclined with respect to true horizontal, but by virtue of the sensing apparatus and leveling apparatus provided herein, the sanding disc will, in effect, be shifted relatively of the now tilted or cocked housing and will thus remain rotating through a true horizontal plane of rotation, notwithstanding the tilting of the main housing. Conversely, if a surface depression is encountered, the sensing means will note this and transmit the appropriate signal to the leveling means to enable the rotating sanding means to continue movement through the same horizontal plane.

It will be seen in this fashion that a perfectly level surface will be obtained, notwithstanding the fact that the larities.

It has been further found that the leveling mechanism employed in this device can be additionally utilized to provide preselected bevels in certain instances of desired application. Thus, for example, bowling lanes could be beveled slightly from right to left or vice versa in certain localized regions.

Additionally, a machine of this character lends itself to the provision of a perfectly horizontal finished surface from a surface that was originally beveled in transverse cross-section, for example. Thus, if a bowling lane had a uniform high point along the right channel and tapered to a lower elevation adjacent the left channel, the machine could be preset to compensate for this bevel, with the result that a perfectly level floor surface could be obtained, notwithstanding the fact that the original surface was beveled.

Production of an improved floor surfacing device having automatic leveling means of the type above described accordingly becomes the principal object of this invention, with other objects becoming more apparent upon a reading of the following brief specification, considered and interpreted in the light of the accompanying drawings.

Of the drawings:

FIGURE 1 is a perspective view of the improved sanding device being shown in use on a floor surface.

FIGURE 2 is a vertical section taken on the lines 22 of FIGURE 1.

FIGURE 2A is a section taken on the lines 2A2A of FIGURE 2.

FIGURE 3 is a vertical section taken on the lines 33 of FIGURE 1.

FIGURE 4 is a vertical section taken on the lines 4-4 of FIGURE 3.

FIGURE 5 is a vertical section taken on the lines 5-5 of FIGURE 4.

FIGURE 6 is a sectional view similar to FIGURE 2 but being on a reduced scale and showing the position of the component parts during the time that a raised surface agea is being encountered by the advancing sanding mac me.

FIGURE 7 is a view similar to FIGURE 6 but showing the sanding unit in engagement with a surface depression and additionally showing the position of the component parts in such condition.

FIGURE 8 is a plan view partly broken away and in section and showing the component arrangement of the components of the inner housing, and further showing the machine preset to remove an existing transverse bevel.

FIGURE 9 is a vertical section taken on the lines 9-9 of FIGURE 8.

FIGURE 10 is a schematic wiring diagram showing the electrical arrangement of certain of the components.

Referring now to the drawings and in particular to FIGURE 1, the improved sanding device is generally designated by the numeral 10, and is shown including a main, or outer, housing 2%, that has associated therewith, in shiftable relationship, an inner housing that is generally indicated by the numeral 3t? in FIGURE 1 of the drawings; the arrangement being such that the main housing 20 is provided with front wheels 21, 21, as well as rear wheels 22, 22., that permit the unit It to be freely moved relatively of a floor surface F, with a pushing handle 24 being provided for this purpose. A control box 25 is provided on the handle 24 for consolidation of electrical controls, in known fashion.

Referring now to FIGURES l, 2 and 3, the outer or main housing 29 is shown as being of generally rectangular configuration in plan so as to include front and rear walls 29a and 29b, as well as opposed side walls 20c and 20d, all of which walls are joined to and connected with the top wall section 20a to form an open, box-like structure as shown in the drawings.

An auxiliary housing 26, of generally U-shaped configuration in plan, is provided for the purpose of enclosing certain motors and controls as is apparent from FIGURES 1, 2 and 3 of the drawings, with this auxiliary housing 26 being fastened to the top wall 201: by the use of known fastening elements that secure the flange portions 26a thereof to said top wall Ztle. Brackets 27, 27 are likewise rigidly attached to the front wall Zlie for the purpose of rotatably supporting the previously described wheel members 21. Similarly, the handle 24 is shown supported by the use of brackets 27a, 27a, that fasten the handle with respect to the top wall 20a by the use of bolts 28, 28 in known fashion. The rear wheels 22, 22 are shown similarly secured to the rear wall 20!) by the use of brackets 29 in known fashion.

In addition to the aforementioned component parts a main sensor assembly, generally designated by the numeral 31, is shown secured by bolts 32, 32 to the front wall 29a with this sensing unit 31 being best shown in FIGURES 3, 4 and 5 and with the same including a surface engaging wheel member 33 that projects from the housing 34 within which the sensor actuating mech anism is contained. In this regard, the sensor mechanism 31 further includes a tubular support 35 within which a shaft 36, that rotatably supports the wheel 33, may be reciprocally moved, with this shaft 36 and wheel 33 being normally urged to a condition of maximum projection by spring member 37. Secured to the shaft 36 by bolts 38 is a gear rack 39 that has the teeth 39a thereof meshed with the teeth 40a of a gear 40.

Referring next to FIGURE 5, it will be seen that the gear 4t) is carried on the same shaft with a larger diameter gear 41, with the result that this gear 41 will rotate in unison with the gear 40. The teeth 41a of gear 41 mesh with the teeth 42a of a gear 42, with this gear 42 being pinned or otherwise fixed to a shaft 43 that serves to actuate precision potentiometers 44, 45 and 46.

These just described precision otentiometers 44, 45 and 46 are preferably identical, and, as will be subsequently described in greater detail, coact with other subsequently to be described sensing means to control the operation of three motor units 54, 55 and 56, with the preferred arrangement being that the precision potentiometer 44 cooperates with a motor 54 which is shown disposed adjacent the forward portion of the housing 20 equidistant between the opposed sides thereof. In like manner, the precision potentiometers 45 and 46 respectively coact, as will be subsequently described, with motors 55 and 56, with these just described motors 55 and 56 being disposed on the side edges of the housing 20 at a point approximately equidistant between the front and rear edges thereof.

Themotor units-54, 55 and 56 are shown respectively connected to right angle gear reduction units 54a, 55a and 56a with these units each having an output shaft (not shown) that is engaged with couplers 54b, 55b and 56b. Support brackets 54c, 55c and 56c are respectively secured to the housing walls 29a, 26c and 20d so as to provide support for certain adjusting mechanisms that are respectively associated with the couplers 54b, 55b and 56!), as will now be described.

Accordingly, and referring first FIGURE 2, it will be seen that the projecting end of coupler 54b receives a shaft 56 that is journaled through support bushings 57 provided on flange 540. The shaft 56 passes through an appropriate opening in the support flange 54c and further has its lower end provided with athreaded portion 53 for purposes that will be described. Received around the threaded shaft portion 58 is a ball screw housing 59 having a projecting flange portion within the projecting end of which is threaded a supporting eyelet 60 with the eyelet 66 having the shank portion 60a thereof threaded into the flange portion 59a as clearly shown in FIGURE 2, and with the eyelet portion 60b thereof having a concave inner surface as shown in FIGURE 2A, so as to be appropriately received around a thrust bearing a that extends between the opposed walls 95b, 95b of a U-shaped retainer block 95, with the bearing 9512 having a convex peripheral surface that complementally engages the convex surface of eyelet 66b so as to absorb thrust forces in known fashion while permitting rotation around pin 95c that is slidably received in elongate slots 95 95] (FIGURE 2A) of walls @515, 951). The base portion 950 of the retainer block 95 is contoured as will be described, for attachment to the inner housing by bolts 95d, 95d.

In this fashion, rotation of the shaft 56 Will cause raising or lowering of the housing 59 with the same being raised or lowered dependent upon the direction of rotation of the shaft 56. It will be noted that during such rotation of the shaft 56 as shown in FIGURE 2, for example, that the inner housing will be able to be properly cocked or angled to the requisite angle by virtue of the pin 9:32 being permitted to slide within the elongated slots 95f, 95 A limit switch bracket 61 depends from the underside of support flange 54c as clearly shown in FIGURE 2, with a limit switch 62 being secured thereto in known fashion and having contact element 62a positioned for engagement with a projecting lug 59b of the housing 59. This limit switch 62 is provided principally for safety purposes and actuation thereof by virtue of contact with the descending lug 591) will cause an immediate reversal of rotational direction of shaft 56 to cause raising of the housing 59 out of a possible danger position. Similar limit switches are contemplated for association with the components that coact with the motors 55 and 56.

It is to be understood tha similar leveling mechanisms are respectively associated with the couplings 55b and 56b.

Thus, the coupler 55b receives a shaft 66 (FIGURE 3) that is threaded at its lower end as at 67. A ball screw housing 63 again moves axially of the shaft 66 upon rotation thereof. Similarly, shaft 70 (FIGURE 3) connects with coupler 56b and has a threaded portion 71 upon which the ball screw housing 72 may axially move upon rotation of shaft 79.

It should be noted, however, that while the thread pitch of the threaded shaft portion 67 and 71 are identical to each other that the thread pitch of the shaft 58 is just double the pitch of the threaded shaft portions 67 and '71, and if reference will be made to FIGURES 6 and 7, it will be seen why there is need for such an arrangement. In this regard, it will be apparent from these figures that the movement of the outer housing 29 is always around a pivot point defined by the rear wheels 22. Thus, if the front edge of the machine 16 is moving upwardly with respect to this pivot point it is apparent that the midpoint between the front and rear of the housing 20 will only move up half as much as the front edge thereof. Accordingly, to compensate and effectuate levelness it is mandatory that the ball screw housing 5? move twice as far axially as do the ball screw housings 68 and 72. While this could be accomplished by making the motor 54 rotate at twice the speed of the motors 5S and 56, it has been found that in normal practice the doubling of the thread pitch will constitute a more eflicient manner of operation since the duration of operation of the motors involved herein is usually very short and in the nature of a fraction of a second. It is also to be understood that equivalent results could be obtained by using different gear reduction units in connection with these just described motors, in which event uniform pitch threads could be provided, with the gear reduction for the front motor effectuating only one-half the amount of motor reduction as the side motors.

In addition to the aforementioned component parts, the top wall Ztie of housing 29 has depending therefrom three auxiliary sensor units that are indicated generally by the numerals 75, '76 and 77. These sensor units are designed to balance out the movement caused by the main sensor 30 and, accordingly, have their projecting plunger elements 75a, 76a and 77a tensionally urged against the ball screw housings 59, 68 and 72, respectively, so as to be movable in response to axial movement of these ball screw housings.

Turning next to a consideration of the inner housing unit 3i it will be seen from FIGURES 1, 2 and 3 that the same includes a main support housing 80, a motor 81 and a sanding or surfacing unit generally designated by the numeral 82; with the arrangement of the above described component parts being such that the housing 86) is fixed against relative rotation with respect to the outer housing 20 but is axially adjustable with respect thereto by means that will be described. Accordingly, the motor 81 will serve to rotate the sanding unit 82 relatively of the inner housing 3%) and the main housing 2%).

In this regard the main housing 85 includes a central hub portion 84 appropriately bored and counterbored so as to have journaled therein the drive shaft of motor 81, with the usual bearing units 85 and 86 being provided and with the motor 81 being secured to the hub 84 by bolts 87, 87 (see FIGURE 3). In actuality, and as best shown in FIGURE 3, the housing 8% includes a plurality of radially extending support girders 88, 88 that are enclosed at their projecting radial ends by a peripheral wall 39 and that are further covered by a top wall section 9%. As shown in FIGURES 2 and 3, this top wall 9% has secured thereto, in known manner, a plurality of L-shaped safety clamps 91, 91, with the right angle portion of these clamps receiving, in each case, an adjustable screw member 52 that bears against top wall 202. In this way a safety catch is provided by the clamp members 91, 91.

In addition to the aforementioned component parts, the top wall surface 9% further includes a plurality of radial slots 93, 93, with one of these slots 93 being shown in FIGURE 1, while other of the slots 93, 93 appear in the sectional view of FIGURE 9.

For the purpose of preventing relative rotation between housings 2i) and 86, the peripheral wall 89 has projecting therefrom three U-shaped retainer block units that are of identical construction so as to be uniformly indicated by the numeral 95. These block units 95, 95 as best shown in FIGURES 2, 2A have been previously recited as being of U-shaped configuration in cross section so as to include a curved base portion 95c which may be secured with respect to the wall 89 by bolts 95d, 95d so that the opposed legs 95b, 95b thereof project radially with respect to the wall 8%, with legs 95b, 95b supporting a pin 95:: that extends therebetween for the purpose of being received in the eyelet 60b of the member 66 as has previously been described.

It will, therefore, be seen that the U-shaped retainer units 95, 95 just described, in fact, serve as support elements to support the inner housing in axially shiftable relationship with respect to the outer housing, and further serve to prevent relative rotation therebeween about their concentric axis. The members 59 and 60 serve also as connecting members between the support elements and the shaft members.

Considering next the disc sanding means 82, the same are illustrated, in the preferred form of the invention, as being of circular configuration and include a rigid base member 96 that has top and bottom faces 96a and 56b. The face 96b is centrally recessed towards the face 96a for the purpose of accommodating a clamping ring 97 that serves to clamp back up and sanding sheets 98 and 99, respectively, in the position shown in FIGURES 2 and 3 of the drawings, with the usual bolts 1%, 199 being employed to effectuate such clamping. Radially extending girders 191, 161 add rigidity to the just described structure and in addition, localized machine surfaces 1b2, 193 and 1&4 are provided on the face 96a (see FIGURE 8). These machine surfaces just described extend radially and have the same angular disposition 6 with respect to each other as do the slots 93, 93. In this fashion upon registry of a slot 93 with one of the machined surfaces or face 96a, a leveling block (see FIG- URE 9) can be temporarily inserted so as to effectuate leveling of the unit, as will be described.

Turning now to FIGURE 10 for a consideration of the electrical circuitry involved between the main sensor 31 and the auxiliary sensor units 75, 76 and 71, it will be seen that the sensor unit 75, for example, operates through a gear 126 to actuate a precision potentiometer 121 that is of the same type and form as has been previously described in connection with the precision potentiometers 44, 45 and 46. It is also to be understood that a similar precision potentiometer is associated in like fashion with each sensor unit 76 and 77;

Again referring to FIGURE 10, it will be seen that the precision potentiometer 121, as well as the precision potentiometer 44, is associated with a current sensitive relay that is generally designated by the numeral 122.

The operation of this electrical arrangement is such that the current sensitive relay 122 includes a coil 123 as well as contacts 124 and 125 that are associated with the leads to the respective poles of the motor 54- in this instance. A swing type contact blade 126 is connected pivotally around the point of connection with a power line 127.

The arrangement of these parts is such that the motor 54 will only operate when there is a condition of unbalance in the current sensitive relay 122. Thus, if the sensor unit 39 is moving upwardly with the result that current is flowing from the precision potentiometer 44 in the direction of arrow 129, the swing plate 126 will swing up to make contact with contact 125. This will cause operation of the motor 54 in this instance.

It has been previously described that as the motor 54, for example, operates, it will move the ball housing associated therewith (the ball housing 59) axially of the threaded shaft 58. As a result of such movement axially, there will be an equivalent movement that will occur with respect to the projecting plunger element 75a of the sensor 75. This movement will cause, through gear 12!), actuation of the precision potentiometer 121, with the result that current will now flow into the current sensitive relay 122 in a direction opposite to the flow indicated by arrow 129. When these current forces, just described, are balanced, the swing plate 126 will return to the full line neutral position and the motor will cease operation.

It is to be understood in this regard that Wheatstone type of bridge circuitry is contemplated for use in connection with such arrangement and in view of the fact that such electrical circuitry is knoum, it is believed that the above basic description will be sufficient to enable a person skilled in the art to practice the invention. It is believed understood that similar precision potentiometers, micro-sensitive relays and interconnecting circuits, are provided for the sensors 76 and 77.

Additionally, it should be understood that cam members and limit switches (not shown) could be associated with the sensor units '75, 76 and 77 in the fashion that the previously described limit switch 62 was associated with the sensor unit 31. In this fashion safety precautions against upward travel of the individual ball screw housing would be provided.

In use or operation of the improved automatic leveling sander It), it will first be assumed that the component parts have been assembled as shown in FIGURE 1 of the drawings, and further that the unit has been positioned on a surface F that is provided with certain surface irregularities in the form of protuberances or cavities. When the surfaces being sanded are perfectly level or horizontal, the component parts will be positioned as shown in FIGURES 2 and 3, with the plane of revolution of the sanding disc $9 being perfectly parallel to the true horizontal plane of the surface that is supporting the main housing 2t through the medium of front and rear wheels 21 and 22.

However, when a raised surface portion such as is shown in FIGURE 6 is encountered, the front wheels 21 will rise up in response to contact with such inclined surfaces, with the rigidity of housing 29 causing uniform raising of the front region even though the protuberance encountered may be localized in the region of only one wheel 21. This raising of the front wheels 21, 21 will be instantaneously detected and compensated for by the trailing sensing wheel 33 and, as shown in FIGURE 6, the shaft 36 and the wheel 33 attached thereto has shifted relatively of housing 20 and is projecting from the main housing 29 to a greater extent than is the casein FIGURE 3. This movement of shaft 36 causes, through gear rack 39, clockwise rotation of gears 49 and all that will, in turn, result in counter-clockwise rotation of the gear 42. The end result of such movement of the gear train is that the precision potentiometers 44, 45 and 46, are energized to cause unbalance in the respective current sensitive relays associated with motors S4, 55, 56. As escribed, this unbalance will result in the motors being actuated to, in turn, result in uniform rotation of the shafts 56, 66 and '70. Such rotation of the just described shafts in the FlGURE 6 situation will result in the ball screw housings 59, 68 and 72 being lowered, with the ball screw housings being lowered twice the distance as are the ball screw housings 68 and 72 due to the fact that the pitch of threaded portion 58 is twice the pitch of threaded portions 67 and 71. This will result in the front portion of the housing St) being lowered around the pivot point defined by the rear wheels 22, and simultaneously therewith a lesser (one-half) amount of lowering will occur with respect to the medial section of the housing 84 As these units are lowered, it, accordingly follows that the spring loaded plungers 75a, 76a and 77a will shift to a condition of greater projection and the result of such movement is to effectuate the immediate transmission, through precision otentiometers such as 121, of balancing current to the current sensitive relays that have been unbalanced by the movement of sensor 30. When the sensor plungers 75a, 76a and 77a have moved to the distance equivalent to the travel of the shaft 36 or thereabouts, the current in the relays will be balanced, and the motors will, accordingly, stop.

It is believed apparent that the FIGURE 7 modification wherein a cavity or undercut area is being encountered operates in just the reverse procedure from that just described, with the sensing wheel 33 being retracted to cause similar retraction of the contact elements of the sensing units 75 and 76 and 77.

It is believed apparent that when the obstructions. described in FIGURES 6 and 7 have been passed and the level surface area has been returned to, that further automatic realignment between the outer and inner housings will occur in view of the fact that the sensing wheel 33 will shift relatively of the main housing during such return, so as to effectuate such immediate adjustment.

Further, and with respect to the safety provisions, previ ously described, it should be noted that in the event that malfunction should occur wherein the shaft 56, for example, would improperly continue to rotate in such direction as to drive the ball housing downwardly beyond the desired amount, the micro switch contact element 62 a will be engaged by the descending protuberance 59b to cause reversal of motor direction as has been previously described. Conversely, if raising beyond the desired level occurs, the limit switches associated with sensors 75, 76 and 77 will be actuated to prevent abnormal damage. In all instances with regard to failure of ball supports 59, 5?, for example, it is believed obvious that the safety clamp 91 will, in any event of such failure, support the inner housing with respect to the outer housing.

In the event it is desired to bevel the angle of cut, it is merely necessary that the appropriate motor be either hand cranked or electrically actuated to lower the appropriate ball screw housing associated therewith. Thus, if it was desired to make the left hand surface of the floor F lower than the right hand surface thereof with respect to the advancing path of movement of the unit 15), it would be merely necessary that the motor 56 be cranked to effectuate lowering of the ball screw housing 72. This would result in the left hand portion of the disc sanding unit 82 being lowered to effectuate the bevel cut.

in the event that it is desired to effectuate a perfectly horizontal cut with respect to an existing surface that is beveled, it is merely necessary that the machine be positioned on the surface and that the sanding disc be manually rotated so that the machine surfaces 101, 192 and 1% thereof are in aligned registry with the slots 93, 93.

At this time the adjustment blocks shown in FIGURE 9 p can be temporarily inserted and manual cranking of the respective motors can be eifectuated until the adjusting blocks indicate that the sanding disc unit 82 is in a truly horizontal position.

For the purpose of permitting additional penetration of depth of cut on successive runs, the electrical control circuit further includes means for providing purely horizontal type of movement of the sanding disc 82. This is achieved principally by known type of electrical bridge circuitry that, in effect, permits the front motor 54 to operate for only one half of the time of operation of the side motors 55 and 56. In this fashion, while the ball screw housing 74 will move twice as far for each revolution as will the ball screw housing 68 and 72, it is believed manifest that all three screw housings will move a uniform amount due to the fact that the shaft 56 will only rotate through half the number of revolutions that are ermitted the shafts 56 and 70.

While the instant invention has been shown to have particular utility with respect to a disc type of sanding operation, it is to be understood that the inventive concept herein disclosed is not intended to be limited to this specific form of disclosure. t is intended, therefore, in this regard to include a drum type of sanding operation in lieu of the purely rotational disc type of sanding illustrated above. Similarly, harder abrasives, and even stone wheels, for example, could be employed for finishing concrete or other hard surfaces having uneven surfaces. The invention also contemplates the provision of a riding sulky formed as an integral part of the unit.

While a full and complete disclosure of the invention has been made in accordance with the dictates of the patent statutes, it is to be understood that the invention is not intended to be limited to the specific embodiment shown herein.

Accordingly, modifications of the invention may be resorted to without departing from the spirit hereof or the scope of the appended claims.

This application is a continuation-in-part of applicants earlier filed application filed December 5, 1960, Serial No. 73,781, now abandoned.

I claim:

1. A self leveling finishing machine for use on surfaces of the character described, comprising: a main housing having surface engaging anti-friction means secured thereto; an auxiliary housing shiftably supported by said main housing; surface finishing means rotatably carried by said auxiliary housing and being disposed for rotational contact with said surface with said auxiliary housing and said surface finishing means shifting relatively of said main housing in unison; sensing means carried by said main housing for engagement with said floor surface and being shiftable relatively of said main housing and said auxiliary housing in response to contact with surface iregularities encountered by said anti-friction means during movement thereof across said surface being finished; and leveling means responding to movement of said sensing means relatively of said main housing and maintaining said auxiliary housing and said surface finishing means in substantial parallelism with said surface, notwithstanding shifting of said main housing upon encountering said irregularities.

2. The device of claim 1 further characterized by the fact that said surface finishing means are disc shaped with one face being disposed in substantially parallel adjacency with said surface. 7

3. The device of claim 1 further characterized by the fact that said surface finishing means include a sanding disc having the abrasive face thereof disposed in substantially parallel adjacency with said surface.

4. The device of claim 1 further characterized by the fact that said leveling means include first and second series of support members respectively can-ied by said auxiliary housing and said main housing; a series of connecting elements respectively connected to said first and second series of support members; and drive means shifting at least one said connector element relatively of at least one said support member whereby relative shifting between said main and auxiliary housings occurs.

5. The devices of claim 1 further characterized by the fact that said leveling means include first and second series of support members respectively carried by said auxiliary housing and said main housing; a series of connecting elements respectively connected to said first and second series of support members; and drive means associated with each of one said series of support members and shifting said connector associated therewith relatively thereof in response to movement of said sensing means relatively of said main housing.

6. The device of claim further characterized by the fact that at least two of said connector members shift through different distances upon operation of the drive means associated therewith for equal periods.

7. The device of claim 5 further characterized by the fact that one said connector moves approximately double the distance that at least one of said remaining connectors moves during operation of said drive means for equal periods of time.

8. The device of claim 5 further characterized by the fact that said sensing means include a contact arm tensionally projecting from said main housing in shiftable relationship therewith; and electrical means actuated by shifting of said contact arm and operating said drive means for a time interval proportional to the amount of shifting movement of said contact arm.

9. A self leveling finishing machine for use on surfaces of the character described, comprising; a main housing having surfaces engaging anti-friction means secured thereto; an auxiliary housing shiftably supported by said main housing; surface finishing means rotatably carried by said auxiliary housing and being disposed for rotational contact with said surface with said auxiliary housing and said surface finishing means shifting relatively of said main housing in unison; and means for maintaining said auxiliary housing in continued substantially parallel relationship with said surface, notwithstanding shifting of said main housing out of substantially parallel relationship with said surface during movement thereof across the same.

10. A self leveling finishing machine for use on a surface of the character described, comprising; a main housing having a substantially circular opening and front, rear and opposed side surfaces; wheels supporting said main housing in a condition of elevated parallelism with said floor surface; an auxiliary housing of generally circular configuration; an abrasive disc rotatably supported by said auxiliary housing; a plurality of shafts carried by one said housing and having threaded portions with the axes of said shafts being substantially parallel to the axis of said circular opening; a plurality of support elements rigidly secured to the remaining said housing and corresponding in number to number of shafts involved;

a plurality of connecting members corresponding in number to the number of shafts and support elements involved with each said connecting member being pivotally secured to one said support element and with each said connecting member having a threaded opening received in threaded engagement with said threaded portion of one said shaft, whereby said connecting members support said auxiliary housing substantially concentrically of said circular opening with said abrasive disc being disposed in substantial parallelism with said surface; and means for rotating said shafts whereby said connecting element may move axially thereof with relative shifting between said main and said auxiliary housings occurring during said rotation.

11. The device of claim 10 further characterized by the fact that said support elements are provided on said auxiliary housing and said shafts are carried by said main housing.

12. The device of claim 10 further characterized by the fact that there are three shafts, three support elements and three connecting members with one connected set of shaft, support elements, and connecting member being disposed adjacent the front surface of said main housing intermediate the opposed edges of said main housing and with the remaining two sets of interconnected shafts, support elements and connecting members being respectively disposed adjacent the side surfaces of said main housing intermediate the front and rear surfaces thereof.

13. The device of claim 12 further characterized by the fact that the thread pitch provided on said shaft disposed adjacent the front edge of said main housing is double the thread pitch provided on the remaining two shafts.

14. A self leveling finishing machine for use on a surface of the character described, comprising; a main housing having a substantially circular opening and front, rear and opposed side surfaces; wheels supporting said main housing in a condition of elevated parallelism with said floor surface; an auxiliary housing of generally circular configuration; an abrasive disc rotatably supported by said auxiliary housing; a plurality of shafts carried by one said housing and having threaded portions with the axes of said shafts being substantially parallel to the axis of said circular opening; a plurality of support elements rigidly secured to the remaining said housing and corresponding in number to the number of shafts involved; a plurality of connecting members corresponding in number to the number of shaft and support elements involved with each said connecting member being pivotally secured to one said support element and with each said connecting member having a threaded opening received in threaded engagement with said threaded portion of one said shaft, whereby said connecting members support said auxiliary housing substantially concentrically of said circular opening with said abrasive disc being disposed in substantial parallelism with said surface; means for rotating said shafts whereby said connecting element may move axially thereof with relative shifting between said main and said auxiliary housings occurring during said rotation; and sensing means carried by said main housing for engagement with said floor surface and being shiftable relatively of said main housing in response to contact with surface irregularities encountered by said wheels during movement thereof across said surface being finished.

References Cited in the file of this patent UNITED STATES PATENTS 2,491,275 Millikin Dec. 13, 1949 2,688,217 Winkler et a1. Sept. 7, 1954 2,913,855 Vinella Nov. 24, 1959 

1. A SELF LEVELING FINISHING MACHINE FOR USE ON SURFACES OF THE CHARACTER DESCRIBED, COMPRISING: A MAIN HOUSING HAVING SURFACE FINISHING MEANS ROTATABLY CARRIED BY SAID TO; AN AUXILIARY HOUSING SHIFTABLY SUPPORTED BY SAID MAIN HOUSING; SURFACE FINISHING MEANS ROTATABLY CARRIED BY SAID AUXILIARY HOUSING AND BEING DISPOSED FOR ROTATIONAL CONTACT WITH SAID SURFACE WITH SAID AUXILIARY HOUSING AND SAID SURFACE FINISHING MEANS SHIFTING RELATIVELY OF SAID MAIN HOUSING IN UNISON; SENSING MEANS CARRIED BY SAID MAIN HOUSING FOR ENGAGEMENT WITH SAID FLOOR SURFACE AND BEING SHIFTABLE RELATIVELY OF SAID MAIN HOUSING AND SAID AUXILIARY HOUSING IN RESPONSE TO CONTACT WITH SURFACE IRREGULARITIES ENCOUNTERES BY SAID ANTI-FRICTION MEANS DURING MOVEMENT THEREOF ACROSS SAID SURFACE BEING FINISHED; AND LEVELING MEANS REPONDING TO MOVEMENT OF SAID SENSING MEANS RELATIVELY OF SAID MAIN HOUSING AND MAINTAINING SAID AUXILIARY HOUSING AND SAID SURFACE FINSIHING MEANS IN SUBSTANTIAL PARALLELISM WITH SAID SURFACE, NOTWITHSTANDING SHIFTING OF SAID MAIN HOUSING UPON ENCOUNTERING SAID IRREGULARITIES. 